1. Field of the Invention
The present invention relates to a suction device for a hand-held power tool, in particular, a compass saw and which is releasably connectable with the power tool and includes a suction blower wheel for producing a suction air stream in a suction path and located in the device housing, a rolling bearing for supporting the suction blower wheel in the housing, a blower shaft for driving the suction blower wheel, and a drive coupling for rotatably connecting the blower shaft with the motor-driven drive shaft of the hand-held power tool.
2. Description of the Prior Art
Suction devices of the type described above are mounted, when necessary, on respective hand-held power tool for aspirating and collecting refuse which is produced during working of workpieces, e.g., chips, drillings, sawdust, etc. With the blower shaft being coupled with the drive shaft of the hand-held power tool, the suction device does not need its own drive, and the suction device can be produced with a low weight and small dimensions.
German Publication DE 40 24 022 discloses a suction device for a drilling or chiseling tool in which the drive coupling is provided by a slot-shaped recess of the drive shaft in which a blade-shaped projection of the blower shaft engages. The blower shaft is supported in the blower housing with a possibility of axial displacement and is pressed into engagement with the drive shaft, in a mounted condition of the suction device, by a spring. With such drive coupling means, a reliable drive of the suction blower wheel with a high efficiency is achieved. However, for certain hand-held power tools, upon mounting of the suction device on the hand-held power tool, certain dimensional tolerances with regard to the axial spacing between the two elements and the coaxial arrangement of both shafts should be maintained which, however, are not always can be insured upon mounting of a suction device on the hand-held power tool each time.
The danger of angular deviation between the two shafts is always present when the suction device is mounted on a hand-held tool, e.g., a compass saw, so that the shafts are arranged transverse to the gravity force during a normal operation. A certain tilting and an axial displacement between the suction device and the hand-held power tool can take place as a result of action of the gravity force on the suction device. These axial and angular deviations produce constraining forces during operation which result in a high wear of components of both the suction device and the hand-held power tool.
Furthermore, the unit blower shaft-suction blower wheel is subjected to high loads, in particular, upon turning the motor on, because the drive of the hand-held power tool, as a rule, is not adjusted for an optimal run of the suction blower wheel. This also increases the wear of the suction device which results in its reduced service life.
Accordingly, an object of the present invention is to provide a suction device in which the drawbacks of the prior art devices are eliminated and the service life of the suction device is increased.